Converting from quads to triangulated mesh
Select your object. Enter edit mode (Tab) and press ctrlT to tirangulate.



The tools has a few options:



Beauty Split the quads in nice triangles, slower method.

Fixed Split the quads on the 1st and 3rd vertices.

Fixed Alternate Split the quads on the 2nd and 4th vertices.

Shortest Diagonal Split the quads based on the distance between the vertices.